Ability to work with only locally saved, favorited wallpapers, cycling them at the same rate. Maybe an "offline" mode?

Once you change the orientation (e.g. from Tiled to Centered) it doesn't take effect until you download a new image.

Doesn't seem to do much for multiple monitors. Couldn't seem to get it to tile images on my non-primary monitor.

Automatically pull from one reasonably safe source with a proposed keyword. Then add a prompt to indicate how users can add more sources and more keywords. This was a little unclear to me on first run.

Autosave any photos to a list that I can then go back through. The program seemed to indicate this was possible via a "history" option but I couldn't find that.

If there's something wrong with the download, you have to manually select cancel. Some kind of note about this or just going on to the next download site would be ideal.

Optional timed breaks (for if you're having to take breaks at your computer)